Missing Check for Updates button on the Router Settings page

The upgrade firmware directions note that the user should select the Check for Updates button to check for new firmware.  My WNDR3400 v3 router does not show that button.

I am looking under http://www.routerlogin.com/ > sign in> Advanced > Administration > Router Update

I manually updated my firmware to 
Firmware Version
V1.0.1.38_1.0.68

However, there is still no Check button for updates.

I am using Win10 with Chrome, both with up to date software

thank you